1. Field
Example embodiments relate to a phase change material, a phase change memory device including the same, and methods of manufacturing and operating the phase change memory device.
2. Description of the Related Art
A semiconductor memory device should be able to store relatively large amounts of data in a relatively small region, maintain stored data for extended periods of time without loss of data even when no power is supplied, and write/read data to/from the semiconductor memory device quickly and precisely. Recently proposed non-volatile memory devices may be highly integrated and have relatively fast operating speeds. An example of the non-volatile semiconductor memory devices may be a phase change random access memory device.
A phase change memory device may store data using the phase change characteristics of a phase change material. In other words, in a phase change material, electrical resistance of the phase change material may differ according to whether the phase change material is in a crystalline state or an amorphous state. The phase change memory device uses this characteristic to store data.
Therefore, operating characteristics of a phase change memory device may be affected by characteristics of a phase change material. GST (Ge2Sb2Te5), for example, an alloy of germanium, antimony, and tellurium, may be the most well-known phase change material. A crystallizing temperature Tc of GST may be about 160° C. A set time of GST, which may be the time required for GST to change its state from an amorphous state to a crystalline state, may be about 150 ns.
Although the crystallizing temperature Tc and the set time of GST may not be significant obstacles for an operation of a phase change memory device including GST, the efficiency of phase change memory devices needs to improve in consideration of rapidly changing demands of the memory device market. Therefore, current research may be focused on reducing the set time of a phase change material used in a phase change memory device and raising the crystallizing temperature Tc of the phase change material to prevent or reduce loss of data due to an operating condition of the phase change memory device.